Fix dark liquids (#6621)

* Update light storage format

2 files changed, 33 insertions, 23 deletions

diff --git a/src/content_mapblock.cpp b/src/content_mapblock.cpp
index 2b0948b3e..8edccf3de 100644
--- a/src/content_mapblock.cpp
+++ b/src/content_mapblock.cpp
@@ -103,7 +103,7 @@ void MapblockMeshGenerator::getTile(v3s16 direction, TileSpec *tile)
 void MapblockMeshGenerator::getSpecialTile(int index, TileSpec *tile, bool apply_crack)
 {
 	*tile = f->special_tiles[index];
-	TileLayer *top_layer = NULL;
+	TileLayer *top_layer = nullptr;
 
 	for (auto &layernum : tile->layers) {
 		TileLayer *layer = &layernum;
@@ -151,7 +151,7 @@ void MapblockMeshGenerator::drawQuad(v3f *coords, const v3s16 &normal,
 //              the faces in the list is up-down-right-left-back-front
 //              (compatible with ContentFeatures).
 void MapblockMeshGenerator::drawCuboid(const aabb3f &box,
-	TileSpec *tiles, int tilecount, const u16 *lights, const f32 *txc)
+	TileSpec *tiles, int tilecount, const LightPair *lights, const f32 *txc)
 {
 	assert(tilecount >= 1 && tilecount <= 6); // pre-condition
 
@@ -281,15 +281,15 @@ void MapblockMeshGenerator::drawCuboid(const aabb3f &box,
 void MapblockMeshGenerator::getSmoothLightFrame()
 {
 	for (int k = 0; k < 8; ++k) {
-		u16 light = getSmoothLightTransparent(blockpos_nodes + p, light_dirs[k], data);
-		frame.lightsA[k] = light & 0xff;
-		frame.lightsB[k] = light >> 8;
+		LightPair light(getSmoothLightTransparent(blockpos_nodes + p, light_dirs[k], data));
+		frame.lightsA[k] = light.lightA;
+		frame.lightsB[k] = light.lightB;
 	}
 }
 
 // Calculates vertex light level
 //  vertex_pos - vertex position in the node (coordinates are clamped to [0.0, 1.0] or so)
-u16 MapblockMeshGenerator::blendLight(const v3f &vertex_pos)
+LightPair MapblockMeshGenerator::blendLight(const v3f &vertex_pos)
 {
 	f32 x = core::clamp(vertex_pos.X / BS + 0.5, 0.0 - SMOOTH_LIGHTING_OVERSIZE, 1.0 + SMOOTH_LIGHTING_OVERSIZE);
 	f32 y = core::clamp(vertex_pos.Y / BS + 0.5, 0.0 - SMOOTH_LIGHTING_OVERSIZE, 1.0 + SMOOTH_LIGHTING_OVERSIZE);
@@ -303,9 +303,7 @@ u16 MapblockMeshGenerator::blendLight(const v3f &vertex_pos)
 		lightA += dx * dy * dz * frame.lightsA[k];
 		lightB += dx * dy * dz * frame.lightsB[k];
 	}
-	return
-		core::clamp(core::round32(lightA), 0, 255) |
-		core::clamp(core::round32(lightB), 0, 255) << 8;
+	return LightPair(lightA, lightB);
 }
 
 // Calculates vertex color to be used in mapblock mesh
@@ -313,7 +311,7 @@ u16 MapblockMeshGenerator::blendLight(const v3f &vertex_pos)
 //  tile_color - node's tile color
 video::SColor MapblockMeshGenerator::blendLightColor(const v3f &vertex_pos)
 {
-	u16 light = blendLight(vertex_pos);
+	LightPair light = blendLight(vertex_pos);
 	return encode_light(light, f->light_source);
 }
 
@@ -367,7 +365,7 @@ void MapblockMeshGenerator::drawAutoLightedCuboid(aabb3f box, const f32 *txc,
 		tile_count = 1;
 	}
 	if (data->m_smooth_lighting) {
-		u16 lights[8];
+		LightPair lights[8];
 		for (int j = 0; j < 8; ++j) {
 			v3f d;
 			d.X = (j & 4) ? dx2 : dx1;
@@ -377,7 +375,7 @@ void MapblockMeshGenerator::drawAutoLightedCuboid(aabb3f box, const f32 *txc,
 		}
 		drawCuboid(box, tiles, tile_count, lights, txc);
 	} else {
-		drawCuboid(box, tiles, tile_count, NULL, txc);
+		drawCuboid(box, tiles, tile_count, nullptr, txc);
 	}
 }
 
@@ -397,11 +395,11 @@ void MapblockMeshGenerator::prepareLiquidNodeDrawing()
 	if (f->light_source != 0) {
 		// If this liquid emits light and doesn't contain light, draw
 		// it at what it emits, for an increased effect
-		light = decode_light(f->light_source);
-		light = light | (light << 8);
+		u8 e = decode_light(f->light_source);
+		light = LightPair(std::max(e, light.lightA), std::max(e, light.lightB));
 	} else if (nodedef->get(ntop).param_type == CPT_LIGHT) {
 		// Otherwise, use the light of the node on top if possible
-		light = getInteriorLight(ntop, 0, nodedef);
+		light = LightPair(getInteriorLight(ntop, 0, nodedef));
 	}
 
 	color_liquid_top = encode_light(light, f->light_source);
@@ -960,7 +958,7 @@ void MapblockMeshGenerator::drawPlantlikeRootedNode()
 		getSmoothLightFrame();
 	} else {
 		MapNode ntop = data->m_vmanip.getNodeNoEx(blockpos_nodes + p);
-		light = getInteriorLight(ntop, 1, nodedef);
+		light = LightPair(getInteriorLight(ntop, 1, nodedef));
 	}
 	drawPlantlike();
 	p.Y--;
@@ -1244,7 +1242,7 @@ void MapblockMeshGenerator::drawNodeboxNode()
 	std::vector<aabb3f> boxes;
 	n.getNodeBoxes(nodedef, &boxes, neighbors_set);
 	for (const auto &box : boxes)
-		drawAutoLightedCuboid(box, NULL, tiles, 6);
+		drawAutoLightedCuboid(box, nullptr, tiles, 6);
 }
 
 void MapblockMeshGenerator::drawMeshNode()
@@ -1330,7 +1328,7 @@ void MapblockMeshGenerator::drawNode()
 	if (data->m_smooth_lighting)
 		getSmoothLightFrame();
 	else
-		light = getInteriorLight(n, 1, nodedef);
+		light = LightPair(getInteriorLight(n, 1, nodedef));
 	switch (f->drawtype) {
 		case NDT_FLOWINGLIQUID:     drawLiquidNode(); break;
 		case NDT_GLASSLIKE:         drawGlasslikeNode(); break;
diff --git a/src/content_mapblock.h b/src/content_mapblock.h
index 5c07077a9..3d196aa99 100644
--- a/src/content_mapblock.h
+++ b/src/content_mapblock.h
@@ -25,8 +25,20 @@ with this program; if not, write to the Free Software Foundation, Inc.,
 struct MeshMakeData;
 struct MeshCollector;
 
-struct LightFrame
-{
+struct LightPair {
+	u8 lightA;
+	u8 lightB;
+
+	LightPair() = default;
+	explicit LightPair(u16 value) : lightA(value & 0xff), lightB(value >> 8) {}
+	LightPair(u8 valueA, u8 valueB) : lightA(valueA), lightB(valueB) {}
+	LightPair(float valueA, float valueB) :
+		lightA(core::clamp(core::round32(valueA), 0, 255)),
+		lightB(core::clamp(core::round32(valueB), 0, 255)) {}
+	operator u16() const { return lightA | lightB << 8; }
+};
+
+struct LightFrame {
 	f32 lightsA[8];
 	f32 lightsB[8];
 };
@@ -49,7 +61,7 @@ public:
 	v3f origin;
 	MapNode n;
 	const ContentFeatures *f;
-	u16 light;
+	LightPair light;
 	LightFrame frame;
 	video::SColor color;
 	TileSpec tile;
@@ -57,7 +69,7 @@ public:
 
 // lighting
 	void getSmoothLightFrame();
-	u16 blendLight(const v3f &vertex_pos);
+	LightPair blendLight(const v3f &vertex_pos);
 	video::SColor blendLightColor(const v3f &vertex_pos);
 	video::SColor blendLightColor(const v3f &vertex_pos, const v3f &vertex_normal);
 
@@ -73,7 +85,7 @@ public:
 
 // cuboid drawing!
 	void drawCuboid(const aabb3f &box, TileSpec *tiles, int tilecount,
-		const u16 *lights , const f32 *txc);
+		const LightPair *lights , const f32 *txc);
 	void generateCuboidTextureCoords(aabb3f const &box, f32 *coords);
 	void drawAutoLightedCuboid(aabb3f box, const f32 *txc = NULL,
 		TileSpec *tiles = NULL, int tile_count = 0);